What does email bounceback mean?

The term “email bounceback” refers to error messages that are received by the email sender when email delivery failed (a.k.a. when an email “bounces”).  Some reasons email bounceback can occur include: an invalid recipient email address,  a recipient’s mailbox is full, or an incompatible protocol was used to send the email.

Bounceback messages will usually include numeric error codes like “550-5.1.1”. The Internet Assigned Numbers Authority maintains a list of SMTP status codes that can be used to interpret these error codes. Additionally, many mail servers include messages with hints on resolving the issue. For example, when sending an email to an invalid recipient at a Google domain, Google’s mail servers will return an error message similar to the one below:

The email account that you tried to reach does not exist. Please try
550-5.1.1 double-checking the recipient’s email address for typos or
550-5.1.1 unnecessary spaces. Learn more at 550 5.1.1
https://support.google.com/mail/?p=NoSuchUser c128si752369pfg.243 – gsmtp
(in reply to RCPT TO command)

As suggested in the bounceback message, the issue could be resolved by correcting the recipient’s email address and resending the email.

Other issues that can lead to email bounceback include:

  • Attachments are too large. This is often associated with a “552” code. To resolve this issue, consider using a file sharing application to share files as links or compressing the file into a smaller format.
  • Links or content that make spam filters reject the message, also often associated with a “552” code. To resolve these issues, try removing hyperlinks, rewording the content, and ensuring the domain in the “From” field matches the SMTP server domain sending the email.
  • The recipient’s mail server is permanently or temporarily down. This is often associated with a “421” code. This issue usually needs to be resolved by recipient.

For further questions or help, please open a support ticket from your HostPapa Dashboard. Follow this link to learn how.

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